What we eat affects our gut microbes, and now researchers can follow both good and bad changes step by step.

“There’s a strong connection between the gut microbiota and human health. What we eat affects our gut microbes, but the challenge is how to capture these changes in real time,” Senior Researcher Carlos Gomez Gallego says.

“Gut microbes can be analyzed from fecal samples, but they are an ‘end product’ that doesn’t really tell us what happens earlier at different parts of our gastrointestinal tract. Animal models, in turn, differ a lot from humans. That’s why the scientific community has started to develop different types of in vitro systems to mimic the human gastrointestinal tract.”

Such in vitro models are also being developed and used at the Institute of Public Health and Clinical Nutrition at the University of Eastern Finland, where Gomez Gallego works. In the lab, food samples, for example, go through different simulated phases of digestion and interaction with the gut microbiota.

“What we want to see is how a food, ingredient or contaminant alters the numbers of different bacteria and the metabolites they produce in the gut, which can be beneficial or detrimental to health. We typically study the changes for 24 hours, as what we eat on average stays in the colon that long, and we can take samples every hour.”

“The gut microbes we are using now are a mix from healthy donors’ fecal samples to ensure a variety of bacteria, but they can be collected from any specific population group, such as lactating infants, depending on the focus of the study,” Gomez Gallego notes.

From orange peels to microplastics

In Gomez Gallego’s research, the focus is mostly on plant-based foods and the various bioactive compounds found in plants. “We can also use the gut model to study the potential of novel foods and ingredients. In a recent study in collaboration with the University of Murcia in Spain, we studied the prebiotic effects of fibers and carotenoids obtained from orange peels.”

Orange peels are an abundant food industry by-product in Spain, and they might be a source of ingredients for enriched foods or supplements. Indeed, the study showed that fibers obtained from orange peel increased the beneficial gut bacteria populations Lactobacillus and Bifidobacterium.

“Local companies around Kuopio have also been interested in testing the potential health impacts of their products, and this is something we hope to do more in the future.”

New results can be expected from studies investigating the interactions of gut microbiota with different types of breads, phenolic compounds from berries and plants, as well as environmental microplastics, among other things.

“With Professor Hani El-Nezamy, we are investigating a phenolic compound called Schisandrin B isolated from Schisandra chinensis, also known as the magnolia or five-flavor berry. It has shown anticarcinogenic properties against colon cancer, and we want to find out more about its gut metabolites that may be mediating this effect.”

Polyamines from mother’s milk

In his earlier research at the Universities of Murcia and Turku, Gomez Gallego has also studied the polyamines and bioactive peptides in breast milk and infant formulas. “I hope to be able to continue and expand that line of research in the future, and we are already developing more accurate polyamine analytics.”

“Those earlier studies showed that these compounds influence the development of gut microbiota and the immune system. However, some formulas contained very little polyamines, compared to normal levels found in breast milk. Maybe for genetic or dietary reasons, some mothers also produced breast milk with very low levels of polyamines.”

Polyamines are essential for tissue growth and regeneration. “Our cells produce them, but dietary polyamines are important to cover the increased requirements in infancy, old age and situations like recovery from injuries.”

“Some gut microbes like lactobacilli and bifidobacteria also produce polyamines, so that’s another reason to enhance their presence in the gut.”

Plant proteins under scrutiny

In collaboration with Professor Marjukka Kolehmainen, Gomez Gallego continues to develop the in vitro gastrointestinal model. “Our first model allowed us to mimic the gastrointestinal transit phase by phase, but now we can simulate a continuous flow.”

What we eat and what kind of gut bacteria we have also affects the well-being of the gut wall. A healthy gut wall acts as a barrier blocking harmful substances from entering the body. “Our in vitro model will soon be able to simulate gut wall interactions as well, as we are going to integrate it with human cell co-cultures modeling the gut barrier.”

Gomez Gallego points out that there is a need for research to facilitate not only healthy food choices but also sustainable food systems. “It’s a reality that the food industry and food consumption have a strong impact on the environment and climate change.”

A transition to more plant-based diets is generally recommended, and many new types of plant-protein foods are now available as alternatives to animal protein. “Compared to meat, an added benefit of plant-based foods is that they contain fibers and bioactive compounds that can be beneficial to health.”

“However, more research is still needed to understand better how different forms of plant proteins behave in our body.”

Food from forests and mountains

The use of local products, as well as by-products, can support sustainability. “That’s why I’m interested in forests as sources of foods like berries and mushrooms, as well as new food ingredients,” says Gomez Gallego, who is a member of UEF’s Forest and Bioeconomy Research Community.

“For example, we have studied by-products of the wood industry that could have antioxidant or anticarcinogenic potential, but there may also be traditional ways to use forest-derived foods that are worth investigating.”

Sustainable food systems are also the theme of an international collaboration that Gomez Gallego coordinates. Involving partners from Peru, Bolivia and Finland, the collaboration aims to increase knowledge of Andean crops such as quinoa and amaranth. “The current farming system is based on a few crops that are really sensitive to climate change, so we wanted to look at alternative, more resilient crops that can be produced globally and sustainably.”

“Students have been really satisfied with the online course we have developed on this topic, and we are planning similar collaboration related to local and traditional crops in South Africa.”